The main goals of this investigation are (1) to demonstrate the existence of a spermatozoal cholinergic system consisting of choline acetyltransferase (ChA), acetylcholine (Ach), cholinergic receptor (AChR) and acetylcholinesterase (AChE), (2) to study the significance of ChA-Ach-AChR-AChE system to sperm mobility, viability and fertilizing capability, and (3) to develop 2-benzoylethyltrimethylammonium and related compounds as inhibitors of sperm ChA and sperm maturation. The spermatozoa from humans, bulls, rats and rabbits will be used in these studies. The Specific Aims include: (1) demonstration of ACh and related compounds in spermatozoa by gas chromatography-mass spectrometry, (2) characterization of sperm ChA, (3) demonstration of the enzymes necessary for the formation of precursors (acetyl-CoA, choline) for ACh synthesis in spermatozoa, (4) evidence for choline uptake system in spermatozoa, (5) characterization of the cholinergic receptor in spermatozoa, and distribution of 14C-nicotine and 125I-alpha bungarotoxin binding proteins in sperm fractions, (6) effects of ChA inhibitors on sperm motility (in vitro), (7) antifertility effects of nicotine and ChA inhibitors in rats, and (8) effects of antifertility agents (cyproterone acetate, alpha-chlorhydrin and trimethylphosphate) on the levels of ACh, ChA, acetate thiokinase and ATP citrate lyase in epididymal spermatozoa in the rat. The results of this investigation may be useful to (1)explain the role of ACh in the regulation of sperm motility, (2) understand certain types of infertility in men who ejaculate immotile sperm, (3) explain transient infertility among male smokers, and (4) develop antifertility agents. According to our investigations, ChA-ACh-AChR-AChE system is present in human, bull and rat spermatozoa. Inhibition of spermic ChA has resulted in the depression of motility.